There is increasing demand for smaller electronic devices, particularly with respect to radio frequency (RF) wireless communication products, for example. These products typically include solid state modules (or packages) having various features, such as electronic circuitry and components attached to and/or embedded in a printed circuit board (PCB), molded compound applied to a surface of the PCB to protect the electrical circuitry and components, and conductive (e.g., metal) pads formed on an opposite surface of the PCB to accommodate subsequent mounting (e.g., using solder) of the modules within the electronic devices, possibly on another PCB.
Tighter placement of the components on a PCB is desirable in order to decrease the size of the module, and thus the electronic device containing the module. For example, surface mount technology (SMT) components are commonly attached to pads on a surface of the PCB. As circuit designs further reduce spaces between SMT components in RF system-in-package (SIP) modules, for example, the accumulated tolerance of tooling, equipment accuracy and raw materials in a conventional fabrication method is too close to the spaces between the SMT components, making it nearly impossible to further reduce the spaces between components. Also, solder paste used to attach the SMT components (as well as other types of components) to the PCB may electrically short after a pick and place process due to the high accumulated tolerance, and solder paste squeezing out from beneath the SMT components may lead to solder electrical shorts after reflow. Currently, attempted solutions include tightening the pick and place accuracy tolerance and force control. However, such solutions are limited by equipment capability, and thus the resulting reduction in accumulated tolerance is minimal.
Accordingly, there is a need to reduce accumulated tolerance, e.g., using existing equipment capability, to enable tighter placement of various components on PCBs.